Global Population Data Quality Ratings
19 April 2020
The accuracy of population data varies widely across countries. The most comprehensive data on the number of people living in a territory and their demographic profile, a vital component for public sector economic and social planning and also for private sector needs, is usually only available from the result of a census.
Most countries conduct a regular population and household census every ten years and some even use a five year cycle. National statistics offices produce only estimates of total population numbers and the demographic breakdown for the intervening years. The accuracy of these estimates depends on the coverage of the last census and the elapsed time since the census, the data and assumptions about births, deaths and net migration and a host of other factors related to the capacity of the national statistical office and its ability to carry out its functions unimpaired by political interference.
There are a number of problems which limit the accuracy of these between census population estimates. National censuses require a large amount of resources to carry out and often vary in accuracy even for developed countries. The Brookings Institution, for example, has expressed fears that political interference and budget restrictions may seriously impair the accuracy of the 2020 United States population census. In many developing countries there are large gaps in terms of the years between holding a census. This means that population estimates made become less and less accurate as time elapses.
Over a sample of 151 countries, the average time between censuses at the end of 2019 was 8.6 years. For 32 countries the elapsed time was 10 years